This invention relates to detecting and separating objects and more particularly to a system and method for detecting or sensing the adequacy of a lining or color on a work piece in a high speed industrial process and removing work pieces that have an inadequate lining or color.
Metal closures for plastic and glass containers are well-known and popular for packaging food and other products. A conventional metal closure for a packaging container often is a screw closure of the kind having a peripheral skirt with an internal lining of a compound. Either after forming or upon assembly of the closure to the neck of a container, the closure internal lining is capable of permanently or semi-permanently conforming to screw thread formations on the container neck or to the container neck or rim. Thus, the lining may form or enhance sealing between the closure and the container such that the container may contain a negative pressure or vacuum therein, which is typically formed during the product filling process. As an example of a lining in this regard, a plastisol compound may be sprayed onto the inside surface of the closure panel, after which the closure having the plastisol may be heat cured before coupling the closure to the container. The lining preferably is substantially deformable such that the lining forms or enhances sealing between the closure and the container neck and/or rim.
A particular type of closure that is suitable for a container having an internal vacuum may be first fitted on the container by the beverage or food manufacturer by a simple pressing and/or twisting action. The closure subsequently may be repeatably removed by the consumer using a conventional twisting action. Such closures are often referred to as xe2x80x9cpress-twistxe2x80x9d closures. Press twist and other vacuum closures are often used for products that are either hot-filled or are thermally pasteurized or sterilized after filling and closing, such as baby food products, preserves, and the like.
Press twist closures often are provided with tamper-evident buttons at the center of their closure panels, which overlie the mouth of the container to which they are fitted. A typical button is an integral, raised circular part of the closure panel, which is held in an inverted, depressed position by the vacuum within the container, but which returns resiliently to its raised position if the vacuum is for any reason subsequently broken or substantially reduced. The button thus indicates, for example, whether the integrity of the seal between the container and the closure has been maintained, or the closure has not made a proper seal with the container. A button disposed in its raised position before an initial opening by an end user may indicate that the product contents of the container may be degraded or spoiled.
Other closures are of the xe2x80x9croll-onxe2x80x9d type, which describes the manner in which the skirt is formed with screw threads after the closure has been applied to the container. Roll-on closures are used extensively for liquid products such as fruit cordials and squashes, spirits and mineral waters, which are typically filled cold, and normally do not require heat treating after filling and closing. Roll-on type closures also form a seal between the closure and the container in order to enhance preservation and freshness of the contents of the container, and to maintain an internal negative pressure or vacuum within the container until the initial opening of the closure by an end user.
The closure lining process typically is a high-speed, automated process in which an uncured plastisol or similar compound is sprayed onto an inside surface of a panel of the closure. Typical through-puts on a belt conveyor or other conventional conveyor may be, for example, 300 to 800 closures per minute, although rates of 2500 closures per minute or more may also be achieved. Inherent in such a high-speed lining coating or spray process, some of the closures produced by such a process will have a lining that is discontinuous or missing, or otherwise falling outside of specified values or tolerances. For example, one of a series of spray nozzles may become clogged, the supply of compound material may become interrupted such that spray is interrupted, a closure may be misaligned with a spray nozzle, or like spraying failures may cause one or a series of closures to be moved from a compound station even though it lacks an appropriate lining.
The problem of a deficient or missing lining is exacerbated because a closure having a deficient or missing lining may produce a disproportionately large economic impact in that the deficient or missing lining is often detected only after filling of a product in the container. Specifically, after a container has been filled with product, a pressure or tamper-evident button on the closure may indicate that the seal between the closure and the container is not air tight. In circumstances in which a deficient closure panel lining is the cause of the insufficient seal, the failure of the seal may cause the entire container and contents to be discarded. Conventional inspection methods generally have been insufficient to fully alleviate this problem.
An automated and accurate system according to an aspect of the present invention is provided for identifying and removing closures having a deficient lining from a conveyor line, thereby eliminating the problematic closures from the line. The system detects or inspects for a lining of a container closure that is formed of a sheet metal and has a panel on an inside surface of the closure. The panel of the closure has a lining formed thereon. The system according to the present invention includes a conveyor for moving plural closures longitudinally and substantially through the system, a color sensor that inspects a panel of each one of the closures on the conveyor for a predetermined color, and a separator that is capable of removing closures that lack the predetermined color. Thus, the system automatically identifies and removes the closures that have the deficient color from the conveyor.
The conveyor may have a conveying surface that supports an outside surface of said closures such that the closures to be inspected have their panel area, on which the lining should be present, facing the color sensor (that is, the panel area is generally facing up). Thus, the conveyor moves the closures from the compound station, through the sensor area at which the panel color is assessed, and to or through the separator region of the system. The color sensor is capable of identifying a sufficient color status that corresponds to a sufficient lining and a deficient color status that corresponds to an insufficient lining. In this regard, the color sensor preferably detects the absence of a suitable lining on the closure by sensing or detecting a predetermined color that corresponds to a substantially bare metal panel. The separator is capable of removing closures having a deficient color status from said conveyor.
The sensor may be calibrated to sense only the color of the bare metal of the interior surface of the closure panel such that the sensor recognizes the bare metal as a deficient color status. Preferably, the sensor includes a RBG system that senses reflected light from the lining on the closure panel. Preferably, the sensor is disposed between the compound station and an oven for curing the lining. Thus, upon recognizing a deficient color status (that is, a color that corresponds to a deficient or missing lining), the sensor may send a signal to a controller. The controller may, after a suitable time delay, send a signal to the separator such that the separator may remove the closure having the deficient color status from the conveyor. Preferably, the separator includes an air jet to blow the closure having a deficient color status from the conveyor.
According to another aspect of the present invention, a method is provided for identifying container closures having a deficient color status from container closures having a sufficient color status. The method includes the steps of: (a) forming a compound on an inside panel surface on substantially each one of the closures in a compound station; (b) conveying the closures from said compound station to a color sensor on a conveyor; (c) sensing a color of each one of the closures by said color sensor; (d) identifying said color as either a sufficient color or a deficient color such that the sufficient color status corresponds to a predetermined amount of compound at a predetermined portion of the panel of each of the closures; and (e) automatically separating the closures having a deficient color status from the closures having a sufficient color status. The method according to the present invention may also include a heating or a curing step that preferably is subsequent to the identifying step.
According to another aspect of the present invention, a system is provided for detecting a predetermined color of decorated metal disks that are capable of being formed into container closures. The system includes a conveyor for moving plural decorated metal disks longitudinally therealong, a color sensor that senses a colored side of each one of said decorated metal disks for a predetermined color, and a separator capable of removing from said conveyor a decorated metal disk having a deficient color status. The decorated metal disks have the colored side oriented upwardly on the conveyor. The color sensor is capable of identifying a sufficient color status that corresponds to a predetermined color on at least a portion of said decorated metal disk and a deficient color status that corresponds to a color that is not said predetermined color.
The separator preferably is an air jet that blows off or removes the deficient decorated metal disk from the conveyor in response to a controller""s signal. The controller receives an appropriate signal from the color sensor and optionally from another sensor (which will indicate when a disk is present). Thus, the system automatically identifies and removes the decorated metal closures that have said deficient color from the conveyor. Further, the system may include a lithographic or other printing station and a shearing station for forming the decorated metal disks from a metal sheet. The system may also include a feed press station for forming the disks into closures. Preferably, the color sensor is disposed between the printing and shearing station, and the feed press station.
According to another aspect of the present invention, a method is provided for identifying a predetermined color of decorated metal disks that are capable of being formed into container closures. The method comprises the steps of (a) conveying the decorated metal disks to a color sensor on a conveyor; (b) sensing a color of each one of the decorated metal disks by said color sensor; (c) identifying the color as either a sufficient color or a deficient color, the sufficient corresponding to a predetermined color, the deficient color corresponding to color that is not the predetermined color; and (d) automatically separating the decorated metal disks having a deficient color status from the closures having a sufficient color status.
The method also may include the step of printing at least one color onto substantially each one of the decorated metal disks in a printing station. The printing encompasses, for example, lithographically printing the at least one color onto substantially each one of the decorated metal disks. Preferably, the predetermined color corresponds to a desired color for the decorated metal disk, whereby the desired color is determined according to the trade dress or desired decoration of a product for which the decorated metal disk is intended.